Ultra-wideband RCS reduction based on reflection cancellation and tunable absorption

This study proposes an ultra-wideband radar cross section (RCS) reduction technique based on reflection phase interference cancellation and tunable absorption. The operational frequency band of the combined structure is enhanced by uniting two overlapped frequency ranges effectively. As proof of concept, a demonstration structure is designed with a stacked chessboard and an active frequency selective surface (AFSS) absorber. The upper chessboard constructed of a square loop and circular patch unit cells can realize destructive phase interference performance at higher frequencies, while the bottom AFSS absorber achieves tunable absorption at a lower frequency range. Three-dimensional scattering patterns at low and high frequencies are analyzed to verify these two different RCS reduction mechanisms. The combined fabrication structure can obtain an ultra-wideband RCS reduction of more than 10 dB from 4.4 to 36.5 GHz, compared to a metallic plate of the same size, indicating good agreement between full-wave simulation and measurements.